Boom controlling device for power cranes



July 10, 1962 w. c. HOLMES BOOM CONTROLLING DEVICE FOR POWER CRANESFiled Jan. 25, 1961 3 Sheets-Sheet l INVENTOR.

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July 10, 1962 w. c. HOLMES BOOM CONTROLLING DEVICE FOR POWER CRANESFiled Jan 23, 1961 5 Sheets-Sheet 2 hm m-I an um Q July 10., 1962 w, c,HOLMES 3,043,445

BOOM CONTROLLING DEVICE FOR POWER CRANES Filed Jan. 25, 1961 3Sheets-Sheet 3 INVENTOR.

WILLIAM nite This application is a continuation in part of my copendingpatent application, Serial Number 697,696, filed November 20, 1957, andnow abandoned, relating to a Boom Controlling Device for Power Cranes.

My invention pertains to means of controlling the lowering of a boom,particularly when the boom carries a heavy load. The invention isintended to be used on the type of power cranes in which it is possibleto regulate the unwinding of the boom-operating cable from its drum bycoupling the drum to the engine of the crane. Ordinarily the lowering ofthe boom is effected by means of a single lever which is operatedmanually and by means of which a satisfactory control of speed in thelowering of the-load may be attained.

When heavy loads are to be carried by the boom, and when the loads haveto be lowered carefully to avoid damaging the load or injuring theworkers in proximity of the place where the load is to be lowered, itwas necessary to couple the drum to the engine of the crane and tocontrol the speed of the lowering of the load by the speed of theengine. In order to do so, the operator of the crane had to actuate aspecial lever serving that particular purpose. As under the stress ofwork or because of a temporary diversion of his attention the operatorwas likely to forget to actuate said lever in order to regulate thespeed of the lowering of the boom by said engine, I have devised meanswhereby the coupling of the engine to the cable drum will be efiectedautomatically, thus rendering the matter independent of the operatorsattention or lack thereof.

'1 shall now describe my improvement with reference to the accompanyingdrawings in which:

FIG. 1 is a diagrammatic presentation of a power crane of the kind inwhich my device is to be employed;

FIG. 2 is a side elevational view of the mechanism controlling theoperation of the boom of the crane, the view including my device;

:FIG. 3 is a partly schematic front elevational view of a brakemechanism shown in combination with the cable drum and means to controlits rotation;

are

FIG. 4 is a side elevational view of the brake wheel of the crane incombination with my device, as seen from line 4-4 of FIG. 2;

FIG. 5 shows the same view as FIG. 4 but discloses my device in adifferent operative position;

FIG. 6 is a top elevational View of elements seen from line 6-6 of FIG.3;

FIG. 7 is a fragmentary perspective view of a clutchshifting fork usedin the crane.

FIG. 8 is a perspective exploded view of the boom lowering controlclutch.

FIG. 9 is a fragmentary vertical section of the boom elevating controlclutch.

FIG. 10 is a fragmentary schematic diagram of the power transmission tothe swing and hoist shafts.

Similar numerals refer to similar parts throughout the several views.

The principal elements of the power crane are shown in FIG. 1 in whichthe crawler-type traction gear is marked 11, and the boom is identifiedby numeral 12, while the cable by means of which the boom may be raisedor lowered is marked 13. Numeral 14 identifies a bucket.

Prior to the description of my device, I will refer to the standardmechanism for raising and lowering the boom. As the mechanism is wellknown, minor details of its construction will be only alluded to orentirely omitted.

On reference to FIG. 2, it will be noted that boom 12 is pivotallymounted at its lower end, as shown at 15, Within a bracket 16 at thefront portion of the turntable 17 which carries the mechanism for theoperation of the crane as a whole. It is. at the upper end of the boomthat said cable 13 is attached thereto. The cable passes over a pulley18 at the upper end of a stationary beam 18A mounted on turntable 17 andis wound upon a drum 19 also mounted upon said turntable.

The rotation of the drum is controlled by means of a gear wheel 20 whichis co-axially mounted with the drum on a shaft 21. The gear wheel is inmesh with an idler 22, and by means of said idler is in engagement witha pinion 82 mounted upon a shaft 80 known as a swing shaft. Mounted onthe shaft and journaled thereon is a brake wheel 24, and encircling thewheel is a brake band which at one end is anchored to a stationarymember 27 mounted upon the upper surface of the turntable.

The other end of the' brake band is connected to a horizontal rod 28. Aspring 29 coiled about the rod and bearing at one end against astationary member 29a keeps the band in a tight frictional engagementwith the rim portion of the brake wheel 24. A ratchet wheel 30 securedto brake wheel 24, mounted upon the same shaft 80 which carries saidbrake wheel, is controlled by an oblong pawl 31 which is pivotallymounted in a bracket 32, as shown at 33. A weight 34a at one end of thepawl keeps it normally in engagement with said ratchet wheel.

The operative action of the swing shaft 80 which is driven by the engineof the crane is control-led by a connective clutch generally indicatedat 34 to which -I shall presently return.

When the boom is to be lowered, it is first necessary to disengage thepawl 31 from the ratchet wheel 30 which rotates with the brake wheel 24.This may be done by kicking the weight upwardly. Next, it is necessaryto loosen the brake band 25 on the brake wheel 24. This is eifected bymeans of a lever 35 which is one of the levers in front of the operator.The lever is mounted pivotally by means of a pin 36, in a bracket 37upon the turntable 17. The lower end of the lever, below the said pin36, is connected pivotally, as shown at 38, to one end of a horizontallink 39 which at its other end is pivotally connected to an L-shapedbell crank 40, as shown at 41 in FIG. 6. The bell crank is pivoted abouta fulcrum pin 45.

Mounted upon the crank, at its mid-portion, as shown in FIG. 3, is avertical member 42, best called a brakerelease lever, the lever beingpivoted upon a pin 43 and including a short arm 44 extending above saidpin and being in engagement with said rod 28. The arm serves to impart alongitudinal movement to the rod against the tension of said spring 29,and thus, to loosen the brake band 25, so that the brake wheel is freeto rotate clockwise. The brake does not restrain the brake wheel againstcounterclockwise rotation.

Secured to the bell crank at the end, remote from the link 39, is thelower end of the stem 46 of a verticallydisposed fork 47. The stem ispivotally mounted, intermediate its ends, upon a pin 48 which projectshorizontallyfrom a boss 49 which forms a part of member 32. The forkincludes two tines 50, each of which terminates at its upper end with aU-shaped yoke 51. Fitting into each yoke is a pin 52 which projectsradially from opposite sides of a band 53 clamped about said clutch 34.

In the cranes at present in use the boom may be lowered under its owngravity. This will take place when the brake band has been loosened andthe pawl 31 has been disengaged from the ratchet wheel 30. For thispurpose, the clutch lever 35 is to be shifted clockwise from its neutralposition, FIG. 2.

In operation, to elevate the boom 12, lever 35, FIG. 2, is manuallyrotated counterclockwise to approximately the dotted line position 35.Link 39 moves to the right, and bellcrank 44 FIG. 6, rotates clockwisecausing the lower end of stem 46 to move outwardly, FIG. 2. The fork 47rotates clockwise about its pivot 48 causing the clutch control band 53to move to the right of the position shown in FIG. 4. This engages theclutch assembly 34 with swing shaft 80 causing rotation of brake wheel24 and the attached gear 32 in a counterclockwise direction. Gear 82through idler gear 22 and gear wheel 20, FIG. 2, thus rotates drum 19winding thereon the cable 13 to elevate the boom.

At the desired height lever 35 is returned to the neutral uprightposition shown. At this point the brake band 25 is effective to preventunwinding of the boom control cable drum 19. Pawl 31-34a is anadditional safety device for mechanically retaining brakewheel 25against rotation in a clockwise direction.

If it is desired to lower the boom in the manner known as precisionlowering, the cable drum is to be coupled, during its cable unwindingrotation, to the engine by means of what is known as a hoist shaft 81.

For this purpose, additional gear wheels are used. One, a sprocket wheel54 is mounted, and journaled at one end of hoist shaft 81. This shaft isdriven through intermediate means by the engine of the crane, ashereafter described. The other wheel, also a sprocket wheel 55, isjournaled as hereafter described upon a shaft 56 and carries a gearwheel 57 for engagement with the gear wheel 20. A chain 58 serves toconnect the sprocket wheels operatively to each other. A clutchgenerally indicated at 59, adapted to be operated manually upon thehoist shaft 81 of the engine by a handle 64 serves as a means ofemploying the power or drag of the engine to control, through saidsprocket wheels and the gear wheel 20, the unwinding rotation of saidhoist drum 19, also referred to as a cable drum. One end of handle 60 ispivotally mounted at 89 to stationary beam 18a, FIG. 2, for swingingmovement in a horizontal plane.

When the operator intends to lower the boom 12 with a load, it isimportant that he shift the clutch 59 on the hoist shaft to itsoperative position before he pulls back the hoist lever 35, FIG. 2, orthe boom, with the load, may suddenly drop down.

I wish to point out that all the above description pertains to amechanism which is now in use and well known. The description wasincluded herein for the understanding of the function of my very simpledevice which I shall now describe in detail.

The device includes a rail 61 disposed vertically and including, at itslower end, -a member 62 turned at right angle thereto. The member isprovided with an eye for connection to the fulcrum pin 48 which supportsthe stem 46 of the fork 47. At the opposite or upper end, the rail isconnected to a bar 63 slanting upwardly towards the handle 60 whichserves to operate the hoist shaft clutch 59. The upper end of the bar 63is provided with an eye for connection by means of a bolt 64 to saidhandle. A coiled spring 65 at one end secured to a clamp 66, upon astationary member 67 of the crane, is connected at the other end to saidmember 63. The spring exerts a pull upon said member 63 and thereby,upon the handle 69, which handle holds the clutch 59 in a normallyinoperative position, as hereafter described.

As shown in FIG. 2, the rail 61 includes a length disposed diametricallywith respect to said clutch 34. Secured to the rail is a flat plate 68which is disposed in a plane parallel to the face of the brakewheel 24,that is 4 at right angle to the swing shaft 8%) upon which the brakewheel is mounted.

Threaded through the plate 63 are two screws 69, each of them extendingtowards the fork 47, one of the screws bearing against the yoke 51 ofthe tine of the fork 47,

while the other screw bears similarly against the yoke of the othertine. Each screw 69 is provided with an adjusting nut 7 0, best shown inFIG. 7.

Thus, the rail 61, including its extension 63, is adapted to be actuatedby the control lever 35 for clutch 34 on the swing shaft 80 of thecrane, and by means of the handle 66 is also connected to the clutch 59on hoist shaft 81 of said crane.

I shall now describe the operation of my device.

It will be assumed that the clutch 59 is in its normal inoperativeposition on the hoist shaft of the crane, while the clutch 34, ofnecessity, would be in its neutral central position upon the swing shaft89 of the crane. The latter is the shaft which supports the brakewheel24 and a pinion 82 in engagement with the gearwheel 22 in mesh with thegear wheel 20 rotating with the cable drum 19.

Now, if it is desired to lower the boom, the operator will disengage thepawl 31 from the ratchet wheel 30 by a swing of the weight 34a upwardly.At this point lever 35 is in neutral position and clutch 34 disengagedvThe operator will pull the lever 35 towards himself in the direction ofthe arrow shown in FIG. 2. As the lever is so moved, the brake band 25upon the brakewheel 24 is loosened in the manner already described, andthe clutch operating stem 46 and connected fork 47 pivotally mounted onthe fulcrum pin 48 is shifted to the position shown in FIG. 5.

As the fork, in response to the movement of lever 35, moves outwardlyfrom its neutral position substantially as shown, FIG. 4, it also swingsthe rail 61 in the same direction as shown in FIG. 5. As a result, theextension 63 at the top of the rail 61 acts upon the handle 60, and bymeans of said handle shifts the clutch 59 to its operative position onthe hoist shaft 81 of the crane. This serves to couple the engine of thecrane to the cable drum 19 by means of the sprocket wheels 54 and and bymeans of the gear wheels 57 and 20 which already have been describedherein. Thus with the brakewheel released, unwinding of drum 19 andlowering of the boom is under the drag or control of the crane engine.

On reversal of the movement of the lever 35 to its neutral position,that is the position shown in FIG. 2, the rail 61 would be swung backunder the pull of tension spring to the position shown in FIG. 4 whenthe handle 69, actuating the clutch 59 would shift said clutch to itsinoperative position. Thus, the object of the device is to connect theswing shaft clutch operating lever, or break release lever 35, with thehoist shaft clutch 59 in such a manner that when for the purpose oflowering the boom the brake 25 is released, the clutch 59 on the hoistshaft 82 will be shifted automatically toits operative position.Furthermore when the clutch lever 35 is shifted back to its neutralposition into operating position 35' for clutch 34, the other clutch 59will be shifted automatically to its inoperative or normal position.

Swing Shaft Clutch 7 an enlarged scale in FIG. 9 and is substantiallyconventional in construction. The said swing shaft clutch 34 includesthe cone element 83 slidably keyed as at 84 upon swing shaft 89 forrotation loosely within the laterally adjustable control band 53 in turnoperated by the tiltable fork 47.

The control ring 53 includes one or more inwardly directed pins 85 whichare loosely positioned within the annular groove in the exterior surfaceof the cone 83, as shown in FIG. 9. Accordingly tilting movementsof thelink 46 and connected fork 4-7 will cause longitudinal shiftingmovements of the control ring 53, as indicated by the double headedarrow, FIG. 9.

Cone 83, FIG. 9, is in an inoperative position and at all times rotateswith swingshaft 80 when swingshaft 80 is rotating. When the cone 83 ismoved to the left, FIG. 9, under the control of the ring 53, it isadapted for operative frictional engagement with the undercut coneelement 86, also forming a part of the clutch assembly 34. At the sametime, axial pressure applied to the said cone element 86 by the cone 83,operatively engages the conventional clutch discs 87 for frictionaloperative engagement with the brakewheel 24 as at 88.

FIG. 9 is a schematic illustration of the general assembly of the clutch34, above described in conjunction with swingshaft 80 and the brakewheel24 journaled thereon, and provides a means of interlocking thebrakewheel 24 with the swingshaft 80. Accordingly, when the cone element83 of clutch 34 has been mechanically moved to the left, correspondingto a forward tilting movement of the control lever 35, FIG. 2, to theposition shown at 35, the swingshaft 80, eifectively rotates brakewheel24 and the gear 82 connected therewith for lifting the boom 12 in amanner above described in detail.

Accordingly the important factor in connection with the presentinventionis that the control lever 35 which is employed for renderingthe clutch assembly 34 operative for the purpose of elevating the boom12, is also employed and tilted in the direction of the arrow shown inFIG. 2 for the double-fold purpose of releasing the brakeband on thebrakewheel 24, and at the same tim actia vating the hoistshaft clutch59.

The hoistshaft clutch 59 under the control of the illusstrative linkageabove described, establishes a connection between the idle sprocket 54on said hoistshaft and the said hoistshaft so that the lowering of theboom and the associated unwinding of the drum '19 is tied into theengine for the crane to thus provide a safety control for the loweringof the boom.

It is recognized that heretofore the operation of the hoistshaft clutch59 was done manually and independently of the operation and applicationof the control lever for releasing the brake. The important factor inconjunction with the present invention is that the same movement of thelever 35 which releases the brake to permit lowering of the boom,simultaneously and automatically activates the clutch 59 on thehoistshaft 81 to control the lowering of the boom.

Hoist Shaft Clutch The hoistshaft clutch 59, heretofore referred togenerally, is shown in detail by way of illustration, FIG. 8, which isan exploded perspective view of the hoistshaft clutch 59 and itsassociation with the sprocket gear 55, illustrative of the method ofcontrol for unwinding of the cable drum 19. The present hoistshaftclutch 59 is illustrative of one form of clutch which will accomplishthis result, it being contemplated that other forms of clutches could,of course, beernployed for the purpose of engaging the idle sprocket 54with the power connected hoistshaft 81 for the control of the loweringof the boom 12 and the corresponding unwinding of the drum 19.

As above described and in normal operation, the clutch 59 is normallyinoperative with the sprocket gear 54 loosely journaled upon therotative hoistshaft 81. As above described, movement of the brakerelease lever 35 in the direction of the arrow shown in FIG. 2 andthrough the linkage, which includes the bellcrank 40, link-46 and thefork 47, and the rail 61, its extension 63 and the handle 60, thehoistshaft clutch 59 is rendered operative so as to be in drivingengagement with the hoistshaft 81.

The assembly of the respective parts is shown in the exploded view, FIG.8. Referring to FIG. 8, hoistshaft 81 has positioned thereover thecentral cylindrical hub 92 of the drum 90, which is keyed thereto as at93, the said drum including upon its interior surface a series of spacedundercut grooves 91. Bearing 94 is slidably positioned over the hub 92and is adapted to receive the elongated sleeve 95-96 over which ismounted and secured the idle sprocket gear 54.

The sleeve portion 96, projecting from the sprocket gear 54, is adaptedto slidably receive thereover the one element 97 which forms a portionof the hoistshaft clutch 59, but which in the exploded view is shownspaced therefrom. Normally this cone in its operative position of theclutch assembly would be provisioned over the sleeve 96 and under therespective heads 102 of the pins 101, which extend through thetransverse apertures #103 in the sprocket gear 54 and through theapertured supports 104 spaced on the opposite side thereof.

FIG. 8 also shows in the exploded view the pivotal arm 105 which isapertured at one end for pivotal mounting upon the pin 101, beingsecured thereto by the pin 1%, the said arm carrying at its opposite endthe dog 107, which against the action of the assembly spring 108 isnormally spaced radially inward from the undercut formation 91 on theinterior surface of the control rum 90. Accordingly in the assembledrelationship of the parts, the cone portion 97 of the clutch ispositioned underneath the pins 101 and the flattened heads 102 so as tonormally hold the said pins 101 in such position against the action ofthe respective spring 108 assembled on the said pins 101 that the saiddogs 107 are spaced from and normally free of the interior controlsurface of the drum 90.

Accordingly, under normal circumstances with the drum 90 rotating in thedirection indicated by the arrow under the control of the hoistshaft 81,the said drum is rotating free of the said dogs 107 and accordingly freeof the sprocket gear 54.

In operation, however, when the handle is moved outwardly from .theposition shown in FIG. 4 to the position shown in FIG. 5, there iseffected a corresponding outward movement to the right, FIG. 8 of thecontrol ring 99 for moving the cone clutch element 97 longitudinallyoutward, partially with respect to the pins 101- 102.

For this purpose, the cone element 97 has anannular grooved flange 98thereon, which is received within the control ring 99 on the handle 60and engaged thereby by the radial pin 100, which projects through thering 99 and down into the grooved flange 98. By this construction,outward movement of the handle causes an outward movement of the coneelement 97 with the result that the respective pins 101-102 arepartially disengaged by the clutch cone 9'7 permitting the springs 108to take over and to bias the dogs 107 into operative engagement with theformed grooved portions 91 in the interior surfaces of the drum 90.

Accordingly when the drum 19 begins to unwind, causing rotation of thesprocket 55 and corresponding rotation of the sprocket gear 54 therewill be a tendency of the sprocket gear- 54 and the associated dogs 107to override the rotation of the shaft 81. This results in effect a driverelation established between the dogs 107 and the drum so that unwindingmovement of the drum 19 is restrained by the drag of the crane enginetransmitted through the operating shaft 81 or hoistshaft 81.

Power Transmission Means carries the idler 115. Idler through the ringgear 116 is adapted to effect rotation of hoistshaft 81. .Idler 115 7through the additional gear 117 is likewise adapted to effect rotationof the swingshaft 80. It is apparent from the increased size of the ringgear 116 with respect to the gear 117 that the said hoistshaft 81 willrotate considerably slower than swingshaft 80.

It Will be understood that the foregoing drawings illustrate merely apreferred embodiment of the present invention by way of illustration andthat other embodiments are contemplated, within the scope of the claimshereinafter set forth.

The primary invention in the present application is particularlydirected to the relationship between the brake and the drum whichcontrols lowering of the boom, the release mechanism for the brake, thehoistshaft connected with the engine of the crane and a normallyinoperative clutch on the hoistshaft associated with an idle gear meansnormally free of the said hoistshaft and wherein a suitable gearrelationship or equivalent connection is established between the saididle gear means and the said drum together with a suitable linkage whichinterconnects the brake release lever and the said clutch on the saidhoistshaft whereby when the brake is manually released the said clutchis simultaneously energized or activated for connecting the said idlegear .to the said hoistshaft for rotation in unison.

By this construction, on release of the brake to the drum, a safetymechanism is provided wherein lowering of the boom is tied into theengine of the crane and the drag thereon employed in effect placing anextra load against unwinding of the boom lowering drum so that the samemay be safely lowered.

While in the present preferred embodiment, one form of linkage has beenshown interconnecting the brake release lever and the clutch mechanism,it is contemplated that other forms of linkage may be employed for thispurpose.

While in the preferred embodiment of the invention, there is shown acombination sprocket gear, sprocket chain and connected tooth gearrelationship between the hoistshaft and the boom controlling drum, it iscontemplated that any other equivalent gear means or other connectingmeans may be employed for this purpose. In other words, the primaryinvention in the present application is the tie-in between the brakerelease leverby a suitable linkage with a clutch mechanism on thehoistshaft by which the unwinding of the drum controlling lowering ofthe boom on the crane may be tied into the crane engine in an automatictype of operation.

Having described my invention, reference should now be had to thefollowing claims.

I claim:

1. In a crane including a base, the improvement comprising a cable drumadapted to control lowering of a boom, a brake wheel, meansinterconnecting said brake wheel and drum for rotation in unison, abrake assembly retainingly engaging said brake wheel, a manual leverpivoted on said base connected to said brake assembly for releasing thesame, a power driven hoistshaft, a normally inoperative clutchadjustably positioned over said hoistshaft, idle gear means on saidhoistshaft responsive to said clutch, additional gear means connectingsaid idle gear means and said drum, and a linkage interconnecting saidbrake release lever and said clutch for simultaneous- 1y interconnectingsaid idle gear means with said hoistshaft upon release of said brakeassembly.

2. In the improvement defined in claim 1, the means interconnecting saidbrake wheel and drum including a series of intermeshing gears.

3. In the improvement defined in claim 1, the means interconnecting saidbrake wheel and drum including a gear on said brake Wheel, a gear onsaid drum, and an idle gear journaled on said base interconnecting saidbrake Wheel and drum gears.

4. In the improvement defined in claim 1, said brake assembly includingspring-biased means frictionally retaining said brake Wheel againstrotation.

5. In the improvement defined in claim 1, said brake assembly includinga spring-biased brake band surrounding and frictionally engaging saidbrake Wheel against rotation, a lever pivoted on said base and at oneend engageable with said brake band for releasing the same, and linkagemeans interconnecting said brake release lever and said latter lever.

6. In the improvement defined in claim 1, said brake assembly includingspring-biased means frictionally retaining said brake wheel againstrotation, a lever pivoted upon said base and at one end engageable withsaid spring-biased means for releasing said brake assembly, and linkagemeans interconnecting said brake release lever and said latter lever.

7. In the improvement defined in claim 1, said idle gear means being asprocket gear, said additional gear means including a gear on said drum,a second sprocket gear and a chain interconnected with said firstsprocket gear, and a gear secured to said second sprocket gear forrotation therewith and in mesh with the gear on said drum.

8. In the improvement defined in claim 1, and spring means associatedwith said clutch normally maintaining the same inoperative relative tosaid hoistshaft.

9. In the improvement defined in claim 1, a stationary support on saidbase, said linkage including an operating handle pivotally mounted atone end upon said stationary support and intermediate its ends connectedto said clutch.

10. In the improvement defined in claim 1, a stationary support on saidbase, said linkage including an operating handle pivotally mounted atone end upon said stationary support and intermediate its ends connectedto said clutch, a second stationary support on said base, and a springinterconnecting said secondary support and said operating handlenormally maintaining said clutch in inoperative position.

1'1. In the improvement defined in claim 1, a stationary support on saidbase, said linkage including an operating handle pivotally mounted atone end upon said stationary support and intermediate its ends connectedto said clutch, a second stationary support on said base, and a springinterconnecting said secondary support and said operating handlenormally maintaining said clutch in inoperative position, said linkagealso including a rail pivotally mounted intermediate its ends upon saidbase, with one end connected to said handle at its other end, and levermeans and a link interconnecting said brake release lever and the otherend of said rail.

12. In the improvement defined in claim 1, the means interconnectingsaid brake wheel and drum including a series of interconnecting gears, apower driven swing shaft, said brake wheel journaled thereon, a clutchon said swing shaft normally in a neutral position and adapted onmovement in one direction to interconnect said swing shaft and saidbrake wheel driving said drum to raise said boom, and an additionallinkage interconnecting said first linkage and said swing shaft clutchwhereby on movement in said one direction from a neutral positionof thebrake release lever, said swing shaft clutch is adapted to raise theboom and on movement in the opposite direction from said neutralposition said lever releases said brake wheel and simultaneouslyinterconnects said hoistshaft clutch with said drum.

13. In a crane including a base, a power driven swing shaft, a firstclutch upon one end thereof, the clutch being normally in neutralposition, a fork in engagement with said clutch adapted to shift theclutch to operative position, the fork including a stem pivotallyconnected to said base at a point removed from said clutch, a powerdriven hoistshaft, a second clutch upon one end thereof, a stationarysupport on said base, an operating handle pivotally secured at one endto said stationary support and intermediate its ends secured radially tosaid second clutch, a rail at one end secured to thestem of the fork ina substantially parallel relation thereto connected at the other end tothe above handle, the rail intermediate its length being connected tosaid fork, a second station ary support, spring means mounted on saidsecond stationary support and adapted to exert a pull upon the handle tokeep the second clutch in its inoperative position, and a manuallyoperative lever movable in opposing directions from its neutral positionand which on movement in one direction interconnects the first clutchwith said swing shaft and on movement in the opposite direction fromsaid neutral position shifts the second clutch to its operativeposition.

14. In a crane including a base, a power driven swing shaft, a firstclutch upon one end thereof, the clutch being normally in neutralposition, a fork in engagement with said clutch adapted to shift theclutch to operative position, the fork including a stem pivotallyconnected to said base at a point removed from said clutch, a powerdriven hoistshaft, a second clutch upon one end thereof, a stationarysupport on said base, an operating handle pivotally secured at one endto said stationary support and intermediate its ends secured radially tosaid second clutch, a movable rail at one end connected to said handle,spring means normally biasing the second clutch and connected handlemaintaining said second clutch in inoperative position, a manuallyoperative lever pivotally mounted on said base movable in opposingdirections from a neutral position, and linkage means interconnectingsaid lever with said first clutch and with said rail, movement in onedirection of said lever interconnecting said first clutch with saidswing shaft, and movement of said lever in the opposite direction fromsaid neutral position shifting the second clutch to its operativeposition.

References Cited in the file of this patent UNITED STATE; PATENTS1,153,034 Crosby Sept. 7, 1915 1,469,579 Borden Oct. 2, 1923 1,470,321Cooper Oct. 9, 1923 2,173,616 Towson Sept. 19, 1939 2,445,116 HustonJuly 13, 1948 2,501,198 Wagner et al. Mar. 21, 1950 2,694,280 ProsserNov. 16, 1954 2,697,948 Holmes et al. Dec. 28, 1954

